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AN EVENT AN ORGANISATION parishealthcareweek.com 2 4 > 2 6 M A y 2 0 1 6 PARIS - PORTE DE VERSAILLES - PAVILLON 1 M E E T T H E F R E N C H H O S P I TA L K E Y P L A Y E R S I N P A R I S EUROPEAN HOSPITAL  Vol 24 Issue 6/15 18 RADIOLOGY & ULTRASOUND Expert reviews the basics of breast elastography Using the entire ultrasound arsenal Maximising mammo on the fro Report: Mélisande Rouger ‘When we talk about elastography, we realise there’s still a confusion surrounding its key concepts,’ said Dr Sergi Ganau Macias, a senior breast radiologist at UDIAT-Parc Tauli Corporation in Sabadell, Barcelona. Elastography was first developed about two decades ago and has been used in breast imaging quite exten- sively. Simply put, it aims at imaging tissue stiffness, which provides addi- tional and clinically relevant informa- tion in a non-invasive, non-irradiating way. Soft and flexible lesions are con- sidered benign, whereas rigidity or stiffness is often an indicator of malignancy. ‘In that sense, elastography is truly a substitute for breast palpation. The elastogram will appear next to the B-mode image and show different Radiologists don’t like to say it, but they hear themselves saying it far too often to women following a mammography exam: ‘The results of the exam are inconclusive.’ Some women need to wait a week or more to receive a letter saying that results were ‘incomplete,’ or worse, that there were ‘abnormal findings.’ The reason so many women hear this uncertain diagnosis is that the frontline technique for breast cancer screening is an X-ray, a one-size-fits- all look at breast tissue that is based on technology going back more than 100 years. While the chance of a woman having breast cancer today is higher than ever, and while the hope of surviving breast cancer is far better, not a lot has changed with the tech- nology to detect cancer. The rise of the digital age has made traditional mammograms more efficient for screening more women more often. But the sensitivity of the exam for helping the radiologist spot cancer remains at about 50 per- cent, which is why so many women are told their exam is inconclusive. Thanks to advances in computer processing power and a new exam technique, two technologies have emerged, greatly improving to as high as 92 percent, the sensitivity of frontline breast screening. This year in Paris, at the French Radiology Congress, two leading clinicians faced off to compare the results of their studies applying the two technologies for frontline mam- mography, digital breast tomosyn- thesis (DBT) and contrast-enhanced mammography, called angiomammo. Tomosynthesis: ‘We find more cancer’ Tomosynthesis was first approved for use in Europe in 2008 and, since then, has steadily built a solid clini- cal case that shows it can detect 40 percent more cancers than tradi- tional two-dimensional (2D) mam- mograms. DBT captures multiple breast images, instead of just one flat image, so that algorithms can be rapidly reconstructed for a three- dimensional (3-D) view of the breast that a radiologist examines in slices as thin as half a millimetre. In clinical studies, women who have a suspicious mass that shows up in the 2-D mammo are not sent home worrying about cancer; instead they are immediately given a 3-D tomosynthesis exam. This com- bination has proven to be powerful not only in detecting cancers, but also for reducing the number of call- back exams. ‘In our daily practice we have fewer uncertainties, eliminate false positives and we find more cancers,’ said Paris-based private cancer specialist Bruno Boyer MD. Where there is a lesion, the tomos- ynthesis image situates it to aid a targeted ultrasound exam though, thanks to the greater specificity of the 3-D image, fewer echo exams are needed, Boyer added. To this point, health insurers have been reluctant to pay for the 3-D DBT exams, calling for more studies of the cost-effectiveness. This practi- cal issue hinders a wider clinical adoption, he pointed out, with many clinics hesitating because of the high cost of purchasing a dedicated machine for 3-D DBT exams, and the longer reading times 3-D images need. Angiomammo: ‘Diagnostic performance identical with MRI’ For the past four years, Clarisse Dromain MD has been deep in clini- cal research using a new technique to detect cancer that may solve the two problems posed by tomosyn- thesis. Angiomammo uses the same X-ray system as traditional mam- mography, but adds the injection of an iodine contrast agent that sud- denly illuminates potentially cancer- ous tumours under a double-energy X-ray burst. ‘Angiomammo in practice is rapid, easy to perform and can be done immediately following a standard mammogram when there are incon- degrees of stiffness,’ said Ganau, who has used elastography for almost a decade. Mapping stiffness can either be estimated from the analysis of tissue strain under a stress or through shear wave imaging. With strain elastography, which could also be called compression or static elastography, the radiologist applies the transducer and compress- es the breast; the applied pressure distorts the breast and lesion to be observed. When the tissue returns to its normal place and shape, the user can assess the elastic modulus. Results are qualitative and can only be measured semi-quantitatively with different ratios or with a colour scale. On the contrary, shear wave or transient elastography enables the user to measure and quantify lesion stiffness without compression, by assessing wave propagation. The technique provides many ben- efits. It adds value to B-mode ultra- sound and is particularly useful in apparently negative ultrasound stud- ies with uncertain clinical or mammo- graphic findings. It can also be used in case of doubt to characterise small size hypo-anechoic lesions (solid or cystic) and iso/hypo-echoic lesions (fat lobules and/or solid lesions). Elastography can bring addition- al sensitivity and/or specificity to B-mode especially in type 3 or 4a lesions, and may help to monitor neoadjuvant treatment when this is not possible with magnetic reso- nance, or when MR is not available. Last, but not least, elastography can help to diminish axilar fine nee- dle punction aspiration (PAAF) false negatives. ‘Elastography nicely complements B-mode imaging and enables to pre- cise indications for biopsy,’ Ganau added. Some studies have shown that elastography limits recourse to biopsy and significantly reduces the number of benign breast biopsy diag- noses (http://www.ncbi.nlm.nih.gov/ pmc/articles/PMC3558110/, Breast elastography: A literature review, A Goddi, M Bonardi and S Alessic). However, despite its high spec- ificity and slight correlation with tumoural phenotypes, the technique will never be a substitute for biopsy, Ganau emphasised. Limitations include industry vari- ability, as manufacturers use differ- ent nomenclature, colour charts and qualitative vs. quantitative scores. Strain elastography is also less repro- ducible than shear wave elastogra- phy. ‘I think a significant downside with elastography is the wide variability between the different models offered by the industry. This versatility com- plicates the conduct of multicentre trials, which would bring vital and much needed evidence regarding elastography’s indications and uses,’ Ganau explained. In addition, cut-off points remain difficult to establish in the case of shear wave elastography. ‘Which one is the ideal cut-off point? When we search for sensitivity and use a low cut-off point, we will find more can- cers and trigger more negative biop- sies; but when we use a high cut-off point, we end up with the opposite problem, i.e. a low cancer detection rate,’ he said. False positives may be due to the presence of calcium, fibromatous component or mucinous carcinoma. Ganau recommends using the whole ultrasound arsenal because techniques are complementary. ‘It’s very important to use Doppler, B-mode imaging, harmonics and elas- tography – in a word,’ he concluded, ‘everything we have to detect cancer as early as possible.’ Although breast elastography entered clinical practice many years ago, a large number of breast radiologists are still unaware of its benefits and have not become familiar with its principles. A dedicated session during the last Spanish Breast Congress (22-24 October, Madrid) aimed to improve knowledge of this technique, by demonstrating the potential in differentiating breast lesion and diagnosing breast tumour, as well as the limitations of elastography Two technologies are vying to become an adjunct for breast cancer screening to deliver conclusive diagnosis faster, John Brosky reports A specialist in breast pathology and gynaecology Sergi Ganau Macias is a senior radiologist at UDIAT-Parc Tauli Corporation in Sabadell, Barcelona. With over a decade’s experience in the use of elastography he has authored many publications and delivered many talks on this subject. He is also a spokesperson for the Spanish Society of Breast Diagnostic Imaging. Using a traditional mammography system, angiomammography applies dual-energy exposures and an injection of a contrast agent to immediately detect cancerous tissue, seen here as a multifocal lesion that has absorbed the contrast agent. 24 > 26 M A y 2016

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